I installed the App and my card have 480 Unified Shaders.
OK. Hence why you are using 2400 thread-concurrency i.e. 5 x 480 = 2400
The info. in the cgminer read me suggests to use 4 or 5 times shaders for best operation. This series of card seems to function better at 3200 and above. I in fact have mine (stable) at 3680.
cgminer -o --scrypt -I 14 -g 1 --thread-concurrency 3680 -w 256 --auto-gpu --gpu-engine 900 --gpu-memclock 800 --no-submit-stale
GPU overclocked by 100 and default memory clock. N.B. These are not my fully overclocked settings, these are safe / stable settings.
Once you have installed MSI Afterburner - try pushing the GPU Core Clock setting up by 5 or 10 to find a stable (highest) value, where you don't see any screen or graphic glitches etc. The higher up you get just add 5 each time instead of 10. If you see a screen error then quickly move it back down by 10 to 25-ish and that will probably be close to the optimal value. You can re-set it and do the same for the Memory Clock and then try both settings together, again reduced by around 10-25 each. If the screen locks up, then you need to hard reset your PC (by holding down the power button) and waiting 10-30 seconds before a re-boot. You have a good amount of system RAM, so you should be OK to move the sliders back down, if your quick, before a full freeze-up (also give the system 30 seconds to respond if this happens).
You can't cause your GPU any real damage by doing this, only increasing voltage etc. will potentially wreck your card or make it unsafe.
I was incorrect in my post above and your default clock speed on that card is also 800 MHz ? So, around 900 to 920 is probably the max. ?
Please post your results so that I might try to help you further. Also, bare in mind that your card does not have a fan, so watch the temp. It should be OK though as it looks to have some crazy heat sink.
This is interesting for me in regards to something that I'm working on with system RAM and scrypt mining.
Thanks